Bicycle Helmet Safety Institute

The Helmet Update by Email

Volume 18, #7 - October 31, 2000

Study Suggests Head Injury Increases Risk of Later Problems

A study published in the October issue of the journal Neurology by the American Academy of Neurology showed a much higher incidence of Alzheimer's disease (AD) and other dementias late in life among WW II veterans who had suffered head injuries during their military service. Although similar results have emerged in other studies, this one took advantage of military records rather than relying on patient recall, increasing accuracy. The increased risk varied with the severity of the injury, rising to four times normal in those who had suffered severe injuries. The study results for mild head injury were "inconclusive." The risk of dementia increased even when a head injury was sustained 40 to 50 years earlier.

The authors conclude "The veterans in this study sustained head injuries in early adult life. Their risk of dementia 50 years later suggests that pathogenesis of the degenerative dementias may trace to origins decades before the appearance of clinical symptoms. This result is consistent with the perspective that AD is a chronic disease that unfolds over many decades, with an extended latent phase as well as a prodromal stage (progressive "age-related cognitive decline") and the stage of fully expressed dementia." The authors reportedly have added in press interviews the caution that the wartime injuries studied may not be typical of injuries sustained in a bicycle crash. This study still has implications for any participant in an activity where head injury is a problem.